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MPC561/MPC563 Reference Manual
MOTOROLA
Digital Subsystem
13.5.4.1 Disabled Mode
When the disabled mode is selected, the queue is not active. Trigger events cannot initiate
queue execution. When both queue 1 and queue 2 are disabled, wait states are not
encountered for IMB3 accesses of the RAM. When both queues are disabled, it is safe to
change the QCLK prescaler values.
13.5.4.2 Reserved Mode
Reserved mode allows for future mode definitions. When the reserved mode is selected, the
queue is not active. It functions the same as disabled mode.
CAUTION
Do not use a reserved mode. Unspecified operations may
result.
13.5.4.3 Single-Scan Modes
When the application software wants to execute a single pass through a sequence of
conversions defined by a queue, a single-scan queue operating mode is selected. By
programming the MQ field in QACR1 or QACR2, the following modes can be selected:
Software initiated single-scan mode
External trigger single-scan mode
External gated single-scan mode
Periodic/Interval timer single-scan mode
NOTE
Queue 2 cannot be programmed for external gated single-scan
mode.
In all single-scan queue operating modes, the software must also enable the queue to begin
execution by writing the single-scan enable bit to a one in the queue’s control register. The
single-scan enable bits, SSE1 and SSE2, are provided for queue 1 and queue 2 respectively.
Until the single-scan enable bit is set, any trigger events for that queue are ignored. The
single-scan enable bit may be set to a one during the write cycle, which selects the
single-scan queue operating mode. The single-scan enable bit is set through software, but
will always read as a zero. Once set, writing the single-scan enable bit to zero has no effect.
Only the QADC64E can clear the single-scan enable bit. The completion flag, completion
interrupt, or queue status are used to determine when the queue has completed.
After the single-scan enable bit is set, a trigger event causes the QADC64E to begin
execution with the first CCW in the queue. The single-scan enable bit remains set until the
queue is completed. After the queue reaches completion, the QADC64E resets the
single-scan enable bit to zero. If the single-scan enable bit is written to a one or a zero by